The present invention relates to a bonded ceramic structure constructed by joining ceramic tubular members, to a ceramic plate, and a method thereof More specifically, the present invention relates to a bonded ceramic structure constructed by inserting ceramic tubular members respectively in holes formed in a ceramic plate and bonding the ceramic tubular members to the ceramic plate, and a method of joining together the ceramic plate and the ceramic tubular members.
Research has been made to develop ceramics and ceramics have been used for forming various structures owing to their high heat resistance, heat insulating capability, electronic and electrical functions, including electrical insulating function, conductivity, magnetic function and dielectric function, and excellent mechanical properties including high abrasion resistance, regardless of their compositions, whether oxide or non-oxide. When used for forming machine parts and structures, ceramic materials must be able to be formed in various shapes, and the ceramic parts or members need to be combined with each other therefore, it is necessary for the ceramic parts to be bonded firmly together, except for those produced by monoblock molding.
Many bonded structures each formed by combining a flat member with a member other than flat members are found in machine parts and structural members. A ceramic heat exchanger for an industrial furnace proposed previously by the applicant of the present patent application in Japanese Patent Laid-open (Kokai) No. 60-62592 employs a device constructed by fastening a large number of tubular members to plate-shaped members.
Trials have been made to apply ceramics to such machine parts and structural members. As a method of fastening ceramic tubular members inserted in holes formed in a ceramic plate to the ceramic plate, as shown in FIG. 11, the method of providing an adhesion layer (12) in the gap between the surface of the hole (11) of the plate (A) and the tubular member (B) has been employed. This method, however, was unable to obtain a sufficient sealing effect and fastening strength, when used in a heat exchanger, for instance. A method disclosed in Japanese Patent Laid-Open (Kokai) No. 60-62592 using a compression spring for joining sphericities also has been employed generally. FIG. 12 is a sectional view of a joint employed in a shell-and-tube heat exchanger disclosed in Japanese Patent Laid-open (Kokai) No. 60-62592. As shown in FIG. 12, spherical surfaces formed in the opposite ends of a tubular member B are fastened to spherical surfaces formed in the respective inner ends of through holes X and X' formed respectively in plates A and A' to form spherical joints Y by mechanical pressing. However, the tubular member is likely to be damaged by thermal stress during operation. Gaps were often formed in the spherical joints due to thermal expansion and thermal contraction; dust contained in the gas supplied to the heat exchanger leaked through the gaps; and dust deposited on the joints deteriorated the sealing effect of the spherical joint.
Accordingly, the development of a bonded ceramic structure comprising component ceramic members fastened together in accurate positional relation, and having uniform joints, and a method thereof has been desired to eliminate such drawbacks in the conventional bonded ceramic structures.